Intraocular pressure in a dog. What is glaucoma in dogs? What is glaucoma

Every owner of a four-legged pet dreams that he stays healthy as long as possible. However, just like humans, animals often experience various diseases. Sometimes the disease appears against the background of the age of the dog, sometimes the hereditary factor becomes the cause of ailments.

Glaucoma in dogs is quite common. This pathology can negatively affect the quality of life of a pet. If the condition of the dog's eyes worsens, then the animal's body cannot function normally. This will lead to additional problems for the owner, who will have to pay much more attention to the helpless creature.

In order for the pet to feel good even in old age, it is important to learn how to recognize glaucoma in dogs in a timely manner. Therefore, it is necessary to study the signs of pathology, varieties and main methods of treatment, as well as prevention.

What is glaucoma

This pathology- This is an eye disease that occurs against the background of excessive eye pressure. This can be caused primarily by the lack of drainage of excess fluid in the area around the visual organs. If the eye is healthy, then the regulation of pressure is carried out in the normal mode. However, with age, the functioning of many systems slows down, excess fluid begins to accumulate in the eyes. Against this background, blood flow is clamped, the optic nerve is damaged, and sometimes even the eyeball.

Glaucoma in dogs is quite dangerous state. If you do not take measures to treat the pathology, that is, big risk that the animal will lose sight during the first year of development of the pathology. Of course, this condition greatly affects the quality of life of your beloved pet. The animal loses orientation and cannot fully move and eat. Therefore, it is important to decide as soon as possible on the treatment of glaucoma in a dog with drugs to improve its condition, etc. If you wait for the disease to disappear on its own, you can cause irreparable harm to your pet's health.

It should also be borne in mind that some breeds of dogs are more prone to pathologies of this type. For example, this disease is most common in huskies, poodles, chow chows and spaniels.

Forms of pathology

There are several varieties of the disease. The primary form of glaucoma in dogs appears without any prerequisites. This means that the disease does not cause previous problems with the visual organs. In this case, visual impairment is due to other problems.

Secondary glaucoma occurs due to inflammatory processes, injuries, neoplasms, cataracts and other problems. Often the cornea of ​​a dog's eye suffers from a congenital pathology. It is worth considering this form of the disease in more detail.

hereditary form

If a we are talking about a genetic disease, it is almost impossible to get rid of it. The only thing left to do is give increased attention healthy eye. Owners of small pets should be especially careful. small size against the background of a genetic predisposition are much more common. However, larger animals may also be at risk. It will not be superfluous to study the pedigree small pet and to clarify whether his parents had vision problems. If such problems have been observed in the past, then special vigilance must be exercised.

Congenital glaucoma is characterized by various defects of the optic nerves. If they are pronounced, then they appear in a puppy from the first days of life. Sometimes about unpleasant pathology pet owners will only find out years later, when heredity begins to make itself felt.

Regardless of the form of pathology, it can be detected in a timely manner. To do this, pay attention to the symptoms of glaucoma in dogs. If you know how the disease manifests itself, then there is every chance to save the vision of your beloved four-legged pet.

Symptoms of pathology

In the early stages of development, the disease rarely manifests itself by obvious signs. Because of this, timely diagnosis is much more complicated. For a long time, the animal may behave normally. This is due to the fact that the pet's body is trying to adapt to changes in vision. In addition, there is compensation due to other senses. Thus, an animal that is already developing glaucoma makes more use of its hearing and its excellent sense of touch and smell.

However, as the disease progresses, the symptoms become more pronounced. There may be redness in the eyes of the dog. Often there is the so-called cobra syndrome. This means that the vessels of the sclera overflow and begin to squirm more. In addition, the tearing of the eyes increases, the corneas become more cloudy. Often the animal has one eye enlarged. This symptom is called "bull's eye".

As the pathology develops, the orientation of the animal begins to deteriorate, and appetite gradually disappears. However, the main danger is that intraocular pressure may increase, and then there is a great risk that the animal will lose sight forever. Therefore, do not delay treatment.

If speak about minor symptoms, then they are so subtle that pet owners simply do not pay attention to them. The only way to see the beginning of the development of pathology in time is to periodically bring the dog for an eye examination, regardless of external state animal.

Reasons for the development of pathology

Most often, animals suffer from this pathology due to age-related changes, so experts recommend to closely monitor the visual organs of pets when they are over 6 years old. In this case, it is recommended to visit the veterinarian annually and check the dog's intraocular pressure.

Also, do not forget that animals, like people, often suffer from diabetes, hypertension, diseases of the cardiovascular apparatus and other systems.

Define exact reasons the development of pathology is very difficult. To do this, it is best to place the pet for some time in a hospital for animals and conduct all the necessary examinations. However, do not despair, complete blindness occurs in dogs only in the most neglected situations. If the pathology is detected in a timely manner, then there is every chance to help your beloved four-legged.

Diagnostic measures

Before treating the eyes of a dog, you need to put correct diagnosis and determine the causes of the development of an unpleasant ailment. To do this, it is best to contact the ophthalmology department to conduct a detailed examination using modern equipment. As a rule, in large clinics, specialists offer to place the dog in a hospital for animals, where experienced specialists can analyze the level intraocular pressure pet, assess the condition of the fundus. Additionally, biomicroscopy of the anterior parts of the visual organs is performed. The veterinarian also checks the optic discs.

On the one hand, glaucoma is dangerous disease which can significantly affect the quality of life of the animal. However, it is not uncommon for dogs to long years lived with such a diagnosis and did not experience serious difficulties. But to qualitatively assess the stage of the disease and possible consequences only an experienced specialist can develop it.

Treatment for glaucoma in dogs

After diagnostic measures, the specialist decides how to help the animal. First of all, you need to reduce the level of intraocular pressure. As a rule, special eye drops for dogs are used first of all. The dosage and the drug itself are selected based on the state of health of the pet, as well as on the stage of development of the disease. It is forbidden for the breeder to prescribe such treatment on his own due to the fact that he cannot determine to what level the intraocular pressure should be reduced in order to alleviate the health of the animal.

It is worth noting that modern drops eye drops for dogs are quite effective. They are convenient to use. In addition, the application medical preparations of this type does not cause much harm to the pet, since the drops have practically no side effect.

If we talk about the dog, then the specialist can prescribe several types of drops. For example, there are special antiglaucoma drugs that help reduce intraocular pressure due to the outflow of fluid. Other means are aimed at reducing the production of the watery component. In particular difficult situations the veterinarian decides to combine several drugs at once.

However, you need to understand that even if the specialist advised how to rinse the eyes of the dog (it is better not to choose the drug itself), then with regular treatment there is only a 50% chance that the negative processes will stabilize. Sometimes it is not possible to preserve visual functions using such methods. In this case, surgery may be required.

Surgical intervention

If the drops were ineffective, and glaucoma reached acute stage, may be required surgical treatment. In this case, excess moisture is removed from the sore eye of the pet using a special drainage system (a kind of filter). If for one reason or another it is impossible to perform a surgical intervention, then evisceration becomes the only way to help the suffering animal. It is a cosmetic procedure during which a silicone implant which completely mimics a healthy eye.

In this case, the animal becomes blind in one eye, but for others, such a defect becomes almost invisible. Only if you get closer to the dog's muzzle by 20-30 cm, you will notice that one eye does not move. Similar procedures are in great demand today.

Preventive actions

So that the owner of the animal does not have to face problems of this kind, it is recommended to do everything possible to minimize the risk of developing pathology. First of all, it is necessary to introduce special supplements into the dog's diet. For example, beta-carotene has a good preventive effect. Also, vitamins C and E will not be superfluous. Such components help to keep the visual organs in good condition for longer.

Even constant conflicts in the family can lead to health problems in an animal. As you know, four-legged pets become depressed and experience severe stress if household members constantly swear and shout. These are not baseless arguments of experts, but a real picture. The fact is that against the background of stressful situations in the body of an animal, oxidative processes begin, which especially actively affect the eye organs.

In addition, it is necessary to ensure that during walks the collar does not squeeze the dog's neck. It is best to use special harnesses that are not able to disrupt blood circulation.

Particular attention should be paid to older pets. It is important to examine your dog's eyes daily and note any changes in your pet's behavior. If the dog began to refuse food and behaves sluggishly, then this is the first sign that her health has deteriorated. In this case, it is recommended to visit the veterinarian as soon as possible.

Preparations

If the treatment is carried out on an outpatient basis, then a 1-2% solution of pilocarpine hydrochloride is used to treat the eyes. Other liquids are also used, the concentration of which is determined by the doctor. Additionally, "Glycerol" and "Diacarb" can be assigned. To try to restore visual function, Riboxin or drugs of the combined group (for example, Fotil) are sometimes used.

Successful treatment of glaucoma

It must be understood that no veterinarian will undertake to guarantee the complete cure of the animal. Of course, a specialist can take measures in order to preserve vision and stop the development of pathology. However, if glaucoma has already passed into the chronic stage, then you will have to spend a lot of money and effort on trying to restore health to your pet's eyes. Therefore, it is best to stop the disease at its initial stage.

The success of the treatment also depends on the skills of the veterinarian. If it's about an experienced specialist, then it will be easier for him to assess the condition of the fundus and identify unpleasant ailment. It is very important that the animal passes all the necessary diagnostic measures. Only on their basis, a specialist can prescribe a particular drug or offer pet owners an operational method for solving the problem.

The good news is that glaucoma usually only affects one eye. Pathology does not spread and does not affect the second eye. Therefore, even if it was not possible to save the visual function, the animal will still be able to see half. However, do not delay treatment. If it is not possible to go to the veterinary clinic on your own, then you should call the veterinarian at home. In no case should you engage in self-diagnosis or treatment.

Glaucoma in small pets is a severe pathology that usually ends in blindness and loss of the eye as an organ. By virtue of such poor prognosis diseases are new medications and advanced areas of glaucoma treatment are of great interest to practicing veterinary ophthalmologists. In this publication, we would like to present new antihypertensive drugs for the treatment of glaucoma in animals: alpha-agonists based on brimonidine.

Selective alpha-2-agonists based on brimonidine (alfagan and combigan eye drops) represent a new generation of antiglucomatous drugs. The alpha-adrenergic agonist brimonidine, having a dual mechanism of action, lowers intraocular pressure by reducing the production of intraocular fluid and improving uveoscleral outflow. By stimulating presynaptic and postsynaptic α-2 receptors, brimonidine reduces the production of intraocular fluid, and by acting on the imidazole receptors of the ciliary body, it improves uveoscleral outflow of intraocular fluid.

It has also been experimentally proven that brimonidine has a direct neuroprotective effect.

The neuroprotective effect of brimonidine is achieved through 4 mechanisms:

• blockade of the entry of calcium ions into the cell, as a result of which its viability increases under conditions of transient ischemia; 1
• inhibition of the release of aspartate and glutamate by the cell, which prevents its apoptosis; 1
• stimulation of the synthesis of neurotrophic factors in the retina, which increases the vital activity of photoreceptors and retinal ganglion cells;
• preservation and improvement of ophthalmohemodynamics by increasing retinal capillary blood flow.

Us for three recent years for the treatment of various forms of glaucoma in more than 100 animals, two alpha-adrenomimetic drugs based on brimonidine in the form eye drops- "alfagan" and "combigan".

Alfagan eye drops are pure adrenomimetic brimonidine, "combigan" is a combination of brimonidine and timolol. Indications for their use were: open-angle, uveal and phacogenous glaucoma. The drugs were prescribed to reduce intraocular pressure and stimulate retinal neurotrophic processes 2–3 times a day, both as monotherapy and in combination with other antiglaucoma drugs.

All animals underwent a complex ophthalmological examination in dynamics, including biomicroscopy of the anterior chamber using Keeler and Shin Nippon slit lamps, direct and reverse ophthalmoscopy of the retina and optic nerve with HEINE Omega 500 and BETA 200 ophthalmoscopes, tonometry with Tonovet devices and a Maklakov tonometer. In some patients, the functional state of the retina in glaucoma was studied using electroretinography on a Retiport veterinary electroretinograph manufactured by Acrivet (Germany).

The analysis of the results showed that both drugs in dogs and cats were effective in the treatment of all types of glaucoma, with the exception of angle-closure glaucoma. It is very important that "alphagan" and "combigan" do not cause pupillary constriction. Therefore, they can be prescribed for uveal glaucoma instead of prostaglandins (travatan, xalatan), without fear of miosis and the formation of synechiae.

In animals, "alphagan" and "combigan" have a hypotensive effect, but in varying degrees. Alfagan is similar in efficiency to 0.25% betoxalol, and was prescribed by us only for initial glaucoma, or for newly diagnosed glaucoma with pressure not higher than 28–30 mm. Combigan has a more pronounced and prolonged antiglaucoma effect compared to alfagan, intraocular pressure during its use decreased by an average of 5 mm Hg. Considering that glaucoma in animals is most often detected on terminal stages and proceeds more malignantly than in humans, in our practice we mainly used combigan, prescribing it 3 times a day. Combigan in almost all animals gave a stable decrease in intraocular pressure, addiction to the drug and a decrease in its effectiveness were observed quite rarely and mainly in terminal or advanced glaucoma. When the effect of monotherapy was insufficient, combigan was combined with carbonic anhydrase inhibitors (azopt and trusop).

Both drugs were well tolerated in animals, cases of irritation, redness, allergic reactions did not occur. Among the adverse events, lethargy and some staggering in three miniature breed dogs (two Yorkies and one Chihuahua) that occurred after instillations of combigan can be noted. We attribute this to the possible general hypotensive effect of the drug. After the abolition of the combigan, these phenomena stopped on their own within a few hours. There were no other complications from the respiratory and cardiovascular systems.

Thus, alpha-agonists are effective drugs in the treatment of glaucoma in animals. They have a pronounced hypotensive effect, are safe, do not cause local irritating and allergenic effects. In initial glaucoma, it is more expedient to use alfagan, a far advanced form requires the appointment of combigan as monotherapy or in combination with carbonic anhydrase inhibitors.

Shilkin A. G., presenter veterinary ophthalmologist, Associate Professor, Candidate of Sciences,
Rotanov D. A., candidate of sciences,
Pavlova T. N., Candidate of Sciences,
Novikova K. A., veterinarian.
Eye Veterinary Center of Dr. Shilkin A.G.

Glaucoma is a disease characterized by an increase in intraocular pressure, leading to impaired visual function. With a recorded incidence of 0.5%, this is the most common eye pathology among dogs. In glaucoma in dogs, intraocular pressure increases due to reduced or no outflow of intraocular fluid from the anterior chamber of the eye. Vision is impaired in glaucoma because ganglion cells die due to the direct action of increased intraocular pressure and the indirect effect of impaired intraocular circulation. For normal vision, adequate functioning of ganglion cells is necessary. In most cases, the diagnosis of glaucoma in dogs is quite simple: intraocular pressure is measured by pressure or tonometry. The value of intraocular pressure is 30 mm Hg. Art. is pathological and diagnostic. This is the easy part of the task. The main difficulty lies not in diagnosis, but in treatment. Before starting appropriate treatment, it is necessary to determine exactly whether the glaucoma is primary or secondary, as well as the potential for preserving vision in the affected eye. The purpose of the following discussion is to simplify clinical assessment glaucoma and the choice of the optimal therapeutic approach.

Classification of glaucoma

Glaucoma in dogs is divided into primary and secondary. It is very important to recognize primary glaucoma because, by definition, it will be bilateral and the initially healthy eye will still be at risk. In about 50% of cases, the second healthy eye with normal pressure also develops glaucoma after 6-12 months. Cause primary glaucoma is a hereditary defect of the iridocorneal angle or trabecular meshwork that prevents the circulation of intraocular fluid. Primary glaucoma is diagnosed when the IOP rises without symptoms. concomitant disease eye. Bitches, middle-aged dogs and certain breeds are particularly susceptible. There are two subtypes of primary glaucoma. Primary open-angle glaucoma (POAG) is the most common in humans, but it is very rare in dogs (mainly Beagles). Angle-closure glaucoma (CLG) is much more common in dogs and primarily affects certain breeds- Cocker Spaniels, Basset Hounds, Miniature Poodles, Boston Terriers, Dalmatians and Northern Dog Breeds. This form of glaucoma is much more resistant to conventional medical treatments than POAG, and has been treated with some success with surgery. But it should be recalled that both types of primary canine glaucoma are fatal diseases that, at best, can be effectively treated for a while. Primary glaucoma is a hereditary disorder, so affected dogs should not be used for breeding.

Secondary glaucoma is usually a unilateral disease, sometimes with the identification and correction of the underlying cause, it is successfully treated and vision is preserved. Secondary glaucoma is caused by eye conditions such as inflammation, neoplasia, and bleeding. Careful examination of the anterior and posterior chambers of the eye with a point light source, magnification, and direct or indirect ophthalmoscopy can reveal these abnormalities. Glaucoma as a consequence of uveitis is the result of decreased intraocular fluid outflow due to peripheral anterior synechia, posterior synechia, or occlusion of the iridocorneal angle by inflammatory cells. Intraocular tumors cause glaucoma when they grow forward and obstruct the outflow of intraocular fluid, or when the iridocorneal angle is occluded due to exfoliation of tumor cells. Hyphema can lead to secondary glaucoma, with bleeding in the anterior chamber of the eye, IOP should be carefully monitored, because shaped elements can interfere with drainage. The main cause of hyphema should always be assumed to be intraocular neoplasms.

Glaucoma is often caused by a luxation or subluxation of the lens, especially in predisposed breeds (terriers, Norwegian Elkhounds, British Spaniels, Welsh Springer Spaniels, Poodles, Beagles). Although this form of glaucoma is always considered to be due to a luxation of the lens, some of the characteristics of this glaucoma are consistent with primary glaucoma. First, although the diagnosis of glaucoma in these breeds is often limited to the detection of lens luxation, removal of the luxated lens does not cure glaucoma in most cases; moreover, glaucoma often precedes anterior lens luxation. Secondly, it is a hereditary disease. Thirdly, and more importantly, this is a bilateral disease and the healthy eye is also at risk. It should be noted that in most dogs, except for terriers, with chronic glaucoma, dislocation of the lens is a consequence of a zonal violation of muscle attachment to the buphthalmic eyeball. However, in dogs predisposed to luxation of the lens, the latter occurs earlier in the course of the disease, when vision is still present, so its removal is an auxiliary procedure in the treatment of this disease.

Diagnostics

Glaucoma cannot be accurately diagnosed and effectively treated without accurate and objective methods measurement of intraocular pressure. Finger tonometry cannot be considered an accurate and predictive method. For the diagnosis and treatment of glaucomatous eyes, instrumental tonometry is needed. The Schiotz tonometer is an inexpensive and reliable instrument that every practicing veterinarian should have. When used correctly, it gives accurate results comparable to applanation tonometers. When using a Schiotz tonometer, a special conversion table must be used to interpret the results. The human conversion table is preferred. IOP in dogs is normally 15-25 mm Hg. Art. with a difference between the eyes of no more than 5 mm Hg.

Tonometry is also used to diagnose uveitis. It should be performed on all reddened eyes without obvious corneal defects. Ocular hypotension (IOP less than 10 mmHg) suggests active anterior uveitis. Severe corneal edema can give false-low results, and anterior lens luxation can lead to false-high results. Note: Schiotz tonometry is contraindicated in deep corneal ulcers, penetrating eye injuries, or recent corneal incisions.

Gonioscopy facilitates examination of the iridocorneal angle. Special lenses are needed to overcome internal reflection in the dog's eye. Although gonioscopy is helpful in further classifying the types of glaucoma, it is not possible to predict which eye will develop glaucoma from the gonioscope appearance of the iridocorneal angle of a dog's eye. Widely used among veterinary ophthalmologists, gonioscopy does not help in the treatment of most clinical cases.

Clinical symptoms of glaucoma

After the diagnosis of glaucoma is made, it is necessary to determine the visual potential of the affected eye by objective tonometric indicators before prescribing treatment. There are a number of clinical symptoms that will assist the clinician in refining this assessment. Next, we will look at the symptoms of acute and chronic disease. In chronic glaucoma, irreversible blindness develops, and the affected eye causes discomfort. Blind eyes in acute glaucoma may still have the potential to see if the disease is in its early stages and it is possible to normalize IOP. Since a strong rise in IOP over several hours can irreversibly impair the visual potential of the eye, acute glaucoma requires emergency care. Symptoms of chronic glaucoma appear over time, but vision is lost irreversibly.

Acute glaucoma
Early in the disease, glaucoma causes acute blindness, eye pain, congestion in the conjunctival and episcleral vessels, and diffuse corneal edema. The pupil is usually dilated and does not respond or almost does not respond to light stimulation. Blindness occurs at the onset of glaucoma due to impaired transport of the axoplasm within the ganglion cell axons and circulation to the optic nerve. Early diagnosis of glaucoma and rapid decline IOP to normal (15-25 mm Hg) blindness may be partially reversible. Glaucoma pain is referred pain. People with angle-closure glaucoma often experience migraine-type headaches. Most dogs usually do not have usual symptoms eye pain such as blepharospasm, epiphora and photophobia. Episcleral congestion causes glaucoma and has characteristic appearance- equally swollen deep episcleral veins, parallel to each other and diverging from the corneal limbus. Corneal edema caused by acute glaucoma is usually diffuse and affects the entire cornea, turning the eye blue. Edema begins due to impaired active endothelial outflow due to increased IOP, and often decreases within a few hours after normalization of intraocular pressure. Mydriasis begins after retinal dysfunction and is caused by pressure obstruction of axoplasmic ganglion cell flow and iris paralysis due to pressure inhibition of the iris sphincter and neuropraxia oculomotor nerve. The pupil and cornea can return normal size after a decrease in IOP. Careful observation of the consensual pupillary reflex (from the affected eye to the normal one) when stimulated by a bright light source helps to decide whether or not the affected eye has vision potential. The blind reflex will help evaluate the optic nerve. A very bright light source (fiber optic or Finhoff transilluminator) is directed to a closed eye, and fast blinking movements should be observed, which are considered a blinding reflex. This test is performed at the initial examination and then repeated after normalization of IOP. Sometimes used to assess functional vision simple tests such as leading an animal over obstacles with a blindfolded good eye. The fundus, when visible, is usually normal. Routine electroretinographic evaluation of photoreceptor cells, bipolar cells, and retinal pigment epithelium, but not ganglion cells, is of little help in diagnosing early glaucoma.

Favorable prognostic symptoms for the seeing or potentially seeing eye are:

1. normal direct and coordinated pupillary reflex (PR),
2. normal blind reflex,
3. normal threat reflex and functional vision test.

Unfavorable symptoms are:

1. lack of a direct and agreed RFP,
2. no blind reflex
3. lack of functional vision or blindness for 3-5 days in history.

Despite the indicativeness of these symptoms, acute glaucoma has no pathognomonic features (as opposed to chronic glaucoma). Since these symptoms can be observed in other eye disorders, tonometry remains the most accurate diagnostic tool. With any threats to the potential of vision, an urgent decrease in IOP should be carried out. Irreversible blindness of the eye will soon become fairly apparent.

Chronic glaucoma
The classical and pathognomonic clinical features of chronic glaucoma are buphthalmia, corneal streaks, and cupping of the optic disc. Buphthalmia occurs due to stretching and thinning of the collagen fibers that make up the cornea and sclera. These changes occur when IOP is elevated over several weeks or months. It should be noted that if the period of increase in IOP is too long to stretch the cornea and sclera, then irreversible changes occur in the retina and optic nerve. In other words, the eye with buphthalmia is almost always blind. Exceptions to this rule are sometimes observed among puppies. In young dogs, buphthalmia can develop within a few days due to the elasticity of the cornea and sclera. In puppies, this elasticity protects the retina. Because the eye grows in size as IOP rises, a single high IOP is not indicative of glaucoma in young animals. Buphthalmia in puppies is reversible if IOP can be normalized. Other exceptions are the Chinese Shar-Pei, Chow Chow and Beagles, which develop stripes on the cornea of ​​their seeing eyes. This retention of vision in enlarged eyes may be due to collagen fiber mucinosis in Chinese Shar-Peis and Chow Chows, which increases the elasticity of the cornea and sclera, and to the insidious nature of open-angle glaucoma, which exclusively affects Beagles.

With buphthalmia, the cornea is stretched, linear ruptures of the Descemet's membrane appear, through which the intraocular fluid penetrates into the corneal sclera. Such linear breaks are called corneal bands, Descemet's membrane bands, or Gaab bands. This is a pathognomonic sign of chronic glaucoma, which is usually observed in blind eyes. Gaab's bands are irreversible changes, they do not disappear after normalization of IOP.

The optic disc cup appears darker than the normal disc due to axonal degeneration and posterior displacement of the perforated plate ethmoid bone. This change is best identified by indirect ophthalmoscopy comparing the normal and affected eye. Over time, the cup becomes visible through the ophthalmoscope, for this IOP must be increased for several weeks or months. In most dogs, the optic calyx is seen in already blind or severely impaired eyes. Other symptoms of chronic glaucoma are corneal neovascularization after buphthalmia-induced keratitis, luxation and subluxation of the lens, cataracts, degeneration vitreous body and generalized retinal degeneration, evidenced by hyperreflectivity of the tapetum and attenuation of retinal vessels.

Glaucoma treatment

Choice proper treatment depends on accurate diagnosis. A treatment acceptable to a seeing eye is not suitable for a blind and sickly one. The owner must know the short-term and long-term forecast, which he is told after complete diagnosis. The goal of treatment depends on the prognosis of vision in the affected eye. In acute glaucoma of the seeing or partially seeing eye, the goal of treatment is to maintain vision and comfort for as long as possible, using all medical and surgical methods treatment. AT acute cases IOP should be reduced quickly, effectively and as safely as possible. The veterinarian and animal owner must understand that an eye affected by primary glaucoma has a very poor long-term prognosis, regardless of the treatment used. With irreversible blindness, the goal of treatment changes. The most important thing a clinician can do to help a dog with a blind glaucomatous eye is to make the eye pain-free because severe hypertension causes severe pain in the eye. This pain is often expressed in drowsiness, depression, isolation, which the owner may not immediately pay attention to. Although POAG in humans usually presents with painless form with loss of vision, most forms of glaucoma in dogs are similar to angle-closure glaucoma in humans, in which patients experience severe pain around the eye accompanied by nausea and vomiting.

Because primary glaucoma is a bilateral disease, most affected dogs go blind in both eyes.

But dogs are not as visually dependent as humans. They have more developed other senses - smell, hearing and touch, therefore total loss vision will not be as debilitating to these animals as it is to humans, especially if the affected eyes are painless. Blind animals that do not experience discomfort can continue to lead an active life.

Therapy for incomplete vision loss

Medical therapy
The goal of medical treatment is to reduce IOP by reducing the volume of intraocular fluid, reducing its production and / or increasing its outflow (table 1).

For acute glaucoma, osmotic drugs are used because they dehydrate the vitreous and reduce intraocular volume. Carbonic anhydrase inhibitors, beta-blockers, and sympathomimetics reduce aqueous humor production. Sympathomithetics and prostaglandin analogues increase the outflow of intraocular fluid.

Osmotic solutions
Hyperosmotic solutions (intravenously - mannitol, orally - glycerin) should be used with a sharp increase in IOP in the seeing or partially seeing eye. These drugs increase plasma osmolality, resulting in an osmotic gradient between the ocular vessels and aqueous humor (mainly in the vitreous body). Hyperosmotic solutions are the most strong remedy to lower IOP and usually lower eshsha 5 hours already 30 minutes after you enter. They are used only in a critical situation, as they lose their effectiveness already at the second and third doses, which makes osmotherapy unsuitable for permanent treatment. Mannitol is prescribed at a dosage of 1-2 g / kg, it is administered intravenously for 20 minutes. Mannitol solution high concentration(20%) can crystallize at room temperature therefore, it is recommended to heat the solution to dissolve the crystals and inject it through a special hematology filter. For 4 hours after the administration of mannitol, the animal is not given water to maintain dehydration inside the eye. Mannitol has never been the only treatment for glaucoma. During or before the administration of mannitol, a carbonic anhydrase inhibitor (see below) should be prescribed, along with one or more topical drugs. Glycerin (50%) is an oral osmotic diuretic that is also capable of causing intraocular hypotension. It is not as effective as mannitol and may cause vomiting. Its dose is 1.4 g/kg, but it is contraindicated in diabetic animals because it may cause hyperglycemia. Within 6-8 hours after treatment, with normalization of IOP, the animal is sent to the veterinarian-ophthalmologist.

Carbonic anhydrase inhibitors
Oral carbonic anhydrase (IC) inhibitors are the mainstay of treatment in animals with glaucoma and are reserved for long-term systemic treatment only. Carbonic anhydrase catalyzes carbon dioxide and water into carbonic acid. IR inhibit the production of intraocular fluid, blocking this process. Since IR reduce the production of intraocular fluid, they are used in all forms of glaucoma. The action of oral IR begins 2-3 hours after administration, maximum effect it reaches after 4-8 hours, while IOP is usually reduced by 20-30%. CIs are the most powerful drugs available for long-term control of IOP. The enzyme carbonic anhydrase is present not only in the tissues of the eye, but also in the kidneys, pancreas, central nervous system, erythrocytes and lungs.

Due to the ubiquitous presence of carbonic anhydrase in the body, IC may have side effects such as polyuria/polydipsia, metabolic acidosis, apathy, lethargy, anorexia, vomiting, diarrhea, and (rarely) blood dyscrasia. These side effects were observed in 40-50% of people taking ICs, they had to stop taking these drugs. With oral administration of IC, the excretion of potassium from the body increased, so hypokalemia was the main consequence of the constant use of IC. Oral potassium supplements are recommended. Although dogs tolerate systemic treatment IR is better than people, the above side effects also occur. Like the pain of glaucoma, these side effects can be subtle and go unnoticed by owners and veterinarians until they are expressed in behavioral changes, reduced activity and appetite. With severe side effects, reduce the dose, prescribe another IC or stop oral administration IR. Dichlorphenamide (Daranid, Merck&Co) at 2-4mg/kg every 8-12 hours is the strongest IR, with few side effects in dogs.

Most dogs tolerate methazolamide and dichlorphenamide better than acetazolamide. Some animals do not tolerate some IR at all, but they perceive others of the same class well. Regardless of the type and dose of systemic CI, 50% of dogs may experience side effects. With minor side effects and improvement in vision, the drugs are not canceled. With severe side effects, soreness of the eyes and the absence of improvement in vision, another therapy is prescribed.

Not so long ago, a new topical IC was released - dorzolamide (Trusorp, Merck & Co). In humans, dorzolamide was administered 3 times a day, was very effective at lowering IOP and did not have the side effects of systemic CPBs. There are few unconfirmed trials of dorzolamide in dogs. It has proven useful in some cases of glaucoma in dogs, but is not able to lower IOP as effectively as oral CIs. In a recent study of people with glaucoma, oral acetazolamide was given with dorzolamide, which produced a very good hypotensive effect, but adding dorzolamide to oral acetazolamide did not produce such a significant reduction in IOP.

Cholinomimetics
Topical cholinomimetics cause pupil contraction, contraction ciliary muscles and increase the outflow of intraocular fluid due to a change in the configuration of the trabecular network. Pilocarpine is a direct-acting cholinomimetic, it is produced in the form of a solution of various concentrations: a 2% solution is most effective for dogs. Theoretically, pilocarpine is the most effective treatment for the most common POAG in dogs. Most forms of glaucoma in dogs are due to narrowing or occlusion of the iridocorneal angle rather than the trabecular meshwork, which calls into question the efficacy of pilocarpine treatment for glaucoma. The advantages of pilocarpine are its effectiveness in the treatment of certain types of glaucoma and its relative low cost. The disadvantages are local reaction and the need to prescribe 3-4 times a day. A 4% pilocarpine gel is produced, which can be placed in a s / c bag 1 time per day. Since pilocarpine crosses the blood-ocular barrier, it should not be used in uveitis or in the treatment of secondary glaucoma.

Indirectly acting cholinomimetics are echothiophate iodide (Phospholine iodide, Wyeth-Ayerst) and demecarium bromide (Humorsol, Merck & Co), they inhibit the action of cholinesterase, therefore, increase the content of endogenous acetylcholine. These drugs are less irritating to the eyes and last longer than pilocarpine, but they are much more expensive. Like pilocarpine, they can activate latent uveitis and exacerbate associated uveitis. Therefore, they are mainly used in primary glaucoma, they are especially useful in primary glaucoma with early luxation or subluxation of the lens, because they cause miosis and prevent the dislocated lens from exiting into the anterior chamber of the eye, which can lead to acute glaucoma with pupillary block, which requires surgical intervention.

Beta blockers
Despite the frequency of prescribing beta-blockers for people with glaucoma, their effectiveness in dogs remains controversial. Beta-blockers lower IOP by reducing the production of intraocular fluid. The most common drug is a 5% solution of Timolol maleate (Timoptik, Merck & Co). Timolol can be used in primary and secondary glaucoma because it reduces aqueous humor production and does not exacerbate uveitis like topical cholinomimetics. Since beta-blockers reduce the production of intraocular fluid differently than CIs, they can be used together with the latter to enhance the hypotensive effect. Timolol is often used as an additional treatment, it is combined with oral IR. It cannot be used as the sole drug for the treatment of glaucomatous eye, but in primary glaucoma it can be used to prevent the development of glaucoma in the other eye.

Sympathomimetics
Adrenergic compounds reduce IOP by stimulating alpha and beta receptors, increasing the outflow of intraocular fluid and reducing its production. As with beta-blockers, they have minimal effect as a single drug, but may be useful as an adjunct to other drugs. They produce epinephrine in eye drops and combined drops with epinephrine and pilocarpine. dipevephrine hydrochloride (Propin, Allegrari) is a precursor of epinephrine, into which it is converted in the anterior chamber of the eye. Dipevephrine hydrochloride is the only drug in this group because it penetrates the tissues of the eye best of all, irritates them less, has a stronger effect and low toxicity. It is more expensive than epinephrine and combined drops with epinephrine and pilocarpine.

Prostaglandin analogs
Latanoprost (Xalatan, Pharmacia & Upjohn) is a prostaglandin analogue designed to lower IOP in humans. Initial reports showed that it was as effective in lowering IOP in people with POAG as timolol maleate 0.5% solution. It reduces pressure by increasing the outflow of intraocular fluid by the uveoscleral route. People are advised to prescribe one drop of the drug 1 time per day at bedtime. The efficacy of this prostaglandin analogue in animals has not yet been fully evaluated, although topical application of PGF2a and similar drugs significantly lowered IOP in rabbits, cats, dogs and monkeys. A side effect of long-term use of this drug in humans has been a change in the color of the iris. The effect of latanoprost has not yet been fully investigated in humans and animals with angle-closure glaucoma. This drug is very expensive, so it can only be the last alternative in the treatment of glaucoma.

Surgery
Surgical procedures for glaucoma can be divided into two categories: surgeries that reduce the production of aqueous humor by destroying part of the ciliary body (cyclodestructive procedures), and surgeries that increase the outflow of aqueous humor by creating surgically new outflow mechanism (filtering procedures). Both types of operations have their advantages and disadvantages. When choosing a surgical type of treatment, the method depends on the specific situation, preference and experience of the veterinary ophthalmologist.

Cyclodestructive procedures are transscleral cryosurgery and laser cyclophotocoagulation. Cryosurgery is effective in lowering IOP, but causes many complications - cataract formation, severe uveitis, hypotension. Most serious complication is temporary, but very sharp rise IOP after surgery, which is very difficult to control and can lead to complete blindness. In cyclophotocoagulation (CPC) Nd:YAG or diode laser is used, after the operation the pressure decreases both in the blind and in the seeing eye. Although a temporary increase in IOP is observed after cryosurgery, it is easier to control it with medication. Cyclophotocoagulation is a non-invasive procedure, but it requires a short general anesthesia. CFC with the help diode laser reduced IOP in 80% of cases and in 50% of cases maintained vision in glaucomatous eyes that were not amenable to medical treatment. This is a relatively new procedure, so long-term results are not yet known. The main indication for laser CPA is the adjunctive therapy of a seeing or partially seeing eye, the IOP of which is not amenable to reduction by medical therapy alone. Laser CFC allows you to save vision in a glaucomatous eye for a longer time than one drug therapy. It is also used for preventive treatment another healthy eye in case of primary glaucoma, but there is a risk of loss of vision in this eye as a result of postoperative pressure increase and uveitis.

Filtering surgical procedures are sclerotomy with iridenclais and gonioimplantable device. In the past, these procedures were rarely successful because the surgically created new aqueous outflow channel soon became clogged with fibrin and inevitably scarred. Recent developments in microsurgical techniques and the use of antiproliferative drugs such as mitomycin-C (Bristol-Meyers Oncology) and 5-fluorouracil (Roche), increased the effectiveness of these procedures, so veterinary ophthalmologists began to use them with new enthusiasm. Because filtering surgical procedures are expensive and cause complications, they are reserved for the treatment of seeing or partially seeing eyes with glaucoma.

Surgical treatment of seeing or partially seeing eyes with dislocation/subluxation of the lens in the early stages of glaucoma remains controversial. There are doubts whether urgent surgical intervention (intracapsular linsectomy) and medical reduction of IOP is required for acute lens luxation in the anterior chamber of the seeing eye to prevent pupil-blocking glaucoma. There is also disagreement among veterinary ophthalmologists regarding the treatment of a shifted lens that remains in the vitreous fossa. The author believes that intracapsular linsectomy of these eyes is unacceptable due to high probability complications - adhesions of the anterior part of the vitreous body with the posterior part of the lens capsule and secondary retinal detachment. From the experience of the author it follows that such eyes remain sighted even for a long time with the help of conservative drug treatment with miotic agents that impede the exit of the lens into the anterior chamber of the eye, as well as other antiglaucomatous drugs. But despite drug therapy, many of these lenses eventually protrude into the anterior chamber of the eye, requiring surgery.

Treatment of blindness and pain syndrome

Medical treatment
Medical long-term therapy does not make sense in the treatment of blind and painful glaucomatous eyes. Most antiglaucoma drugs are expensive and ineffective in this case. But more important is the systemic toxicity and side effects of all drugs, including topical drugs. Oral RIAs are the most effective drugs against glaucoma, but they also have very strong side effects. Many people develop headaches above the eyes and blurred vision after treatment with pilocarpine. Topical application of beta-blockers may cause cardiovascular or respiratory reactions. According to the author, due to the high cost and side effects, the indication for the use of any drugs against glaucoma can only be the preservation of vision in eyes with glaucoma. But if vision is already lost and the eye hurts, then for the animal and its owner there will be the best way out the use of preserving surgical procedures that make the blind eye painless and provide an opportunity to forego ongoing medical therapy.

Surgery
Preserving surgical procedures in blind eyes with glaucoma are enucleation, intraocular evisceration-implantation, and pharmacological ablation of the ciliary body by injecting gentamicin into the vitreous body. It is preferable to perform intraocular evisceration-implantation in eyes blinded by primary glaucoma. This procedure always has successful results and gives a completely cosmetic look and comfort to the eyeball, which does not require further treatment. It follows from the author's experience that evisceration-implantation saves the life of dogs with primary glaucoma, because almost all owners want to take care of a blind animal, but the sight of a dog without eyes may become unacceptable for some people.

Another preference of the author is intravitreal injection of gentamicin. Gentamicin is toxic to the epithelium of the ciliary body, which produces intraocular fluid, but it is also toxic to the retina, so it is used only for blind eyes. This drug should be used very carefully if suits the eye active inflammation because it can potentiate uveitis. It is never used for intraocular tumors or for eyes with glaucoma of unknown cause. The advantage is that this procedure can only be performed under sedatives and local anesthesia, which eliminates general anesthesia and greatly reduces its cost. Her frequent complications are a small decrease in VGD, chronic persistent uveitis, which can lead to hypotension, also causing pain, recurrent hemophthalmos and phthisis eyeball. These complications should be discussed with the owner prior to injection as they are 30-40% likely to occur. Despite these complications, pharmacologic ciliary body ablation is a necessary treatment in some situations. Injection of gentamicin into the vitreous body is indicated only after setting accurate diagnosis last stages primary glaucoma, which is confirmed by tonometry. It is contraindicated for seeing eyes and eyes with intraocular tumors or infections.

Therapeutic approach

The doctor should explain to the owner of the animal that primary glaucoma in dogs is an incurable disease. The goal of treatment is to preserve vision for as long as possible, using medication and/or surgery, and also if only one eye is affected, then the preservation of vision or slowing down its loss in the other eye. Often multidrug therapy is needed. The most powerful antihypertensive drugs are carbonic anhydrase inhibitors. At local use IR are effective only when IOP is less than 35-40 mm Hg. Art. Most animals tolerate oral IC administration and one or two topical agents from different classes better. The author prefers a combination of oral IR and timolol. Most glaucoma medications lose their effectiveness over time. If the pressure begins to rise despite medical therapy, surgical intervention is indicated. When the eye becomes irreversibly blind and sore, saving operations are indicated. Eyes with glaucoma need constant monitoring and tonometry every 3 months. Moreover, the owner should be informed about the early symptoms of glaucoma and advised to contact the veterinarian for any redness, pain, clouding or change in vision in the affected and unaffected eyes. In dogs with primary glaucoma, prophylactic treatment with topical beta-blockers, sympathomimetics, or miotic drugs may slow the development of glaucoma in the other healthy eye, but cannot prevent glaucoma.

Despite recent advances in the treatment of glaucoma, this disease remains one of the most difficult, both for the doctor and for the owner. Although many antiglaucoma drugs are currently available, the clinician should be aware that their efficacy and safety have been tested in humans and dogs with POAG, and not in glaucoma and other forms of it. In the treatment of all cases of glaucoma, prompt consultations with veterinary ophthalmologists are necessary.

Glaucoma, an increase in intraocular pressure (IOP), is one of the leading causes of irreversible blindness in dogs. This disease is accompanied by an increase in intraocular pressure and an increase in the eyeball. There is also dropsy of the eye, which differs from glaucoma in that it is a consequence of inflammatory processes, primarily of the vascular tract.

Since glaucoma can lead to blindness within 24-48 hours of onset, it requires urgent aggressive medical therapy and immediate referral to a veterinary ophthalmologist. It is easy to detect clinically. It should be a rule to examine all animals with hyperemia of the eyeball, in which ulcer and infection of the cornea and purulent processes have been excluded, for the presence of glaucoma.

What can a dog owner do?

Blurred eyes in dogs can be caused by various reasons and in most cases the owner cannot provide assistance on their own. It is important to clarify the diagnosis by measuring intraocular pressure - glaucoma in a dog is accompanied by an increase in pressure. You can try to carry out diagnostic treatment - the pet is given diacarb (kosopt, azopt or another drug). This drug reduces intraocular pressure, so if the treatment is effective, glaucoma can be assumed.

Contact your veterinarian immediately the best solution with cloudy eyes in a dog.

The complexity of providing assistance lies in the lack of veterinary ophthalmologists. Even in large cities, there is a shortage of specialists who can correctly carry out diagnostic measures and treatment. But in any case, the veterinarian is much more competent in the treatment of the dog.

Owners can conduct their own symptomatic treatment. Tetracycline and other ointments are placed in the eye, the conjunctiva, Tobrex, Vizin and others are washed. Positive dynamics is possible, but its probability is extremely small. In addition, it should be remembered that glaucoma is accompanied by a strong pain reaction, the dog suffers, and in most cases, if not provided emergency help, you have to remove the eye.

In most cases of glaucoma in dogs, the eye must be removed.

What causes cloudy eyes?

The main cause of glaucoma is a violation of the filtration between the anterior and internal department eyeball on the basis of various endogenous and exogenous diseases. Endogenous diseases that contribute to the development of glaucoma include hepatitis, diabetes, diseases of the gastrointestinal tract, genitourinary system and hormonal status. To exogenous reasons include trauma to the eyeball, keratitis, iritis, cataracts, intraocular tumors.

Glaucoma in dogs is divided into primary and secondary. It is very important to recognize primary glaucoma because, by definition, it will be bilateral and the initially healthy eye will still be at risk. In about 50% of cases, the second healthy eye with normal pressure also develops glaucoma after 6-12 months.

Glaucoma is caused by a blockage in the outflow of aqueous humor from the eye. Aqueous moisture normally flows out of the eye through the angle of the anterior chamber of the eye and is absorbed into the vessels of the venous plexus of the cornea. Bitches, middle-aged dogs and certain breeds are particularly susceptible.

Types of blurred eyes:

• phacotopic glaucoma. This is the luxation of the lens into the anterior or posterior chambers of the eye. It is associated with breed weakness of the zinn ligaments, for example, in spaniels or welsh terriers. Subluxation and then luxation of the lens into the anterior chamber lead to a mechanical blockade of the outflow pathways of the intraocular fluid by the lens.
• phacomorphic glaucoma. More common in cats. When a cataract matures, the soft rounded lens begins to accumulate moisture, the so-called spherophakia is formed. The anterior chamber becomes smaller, a relative pupillary block occurs. The formation of a swelling cataract provokes the occurrence of an acute or subacute attack of angle-closure glaucoma.
• phacolytic glaucoma. It develops in animals with overripe cataracts. Through small defects in the altered lens capsule, large protein molecules penetrate into the anterior chamber of the eye. As a result, the outflow tract becomes clogged and intraocular pressure rises. However, phacolytic glaucoma is rare in dogs and cats. Complete lysis of the lens is often asymptomatic.

Primary glaucoma is a hereditary disorder, so affected dogs should not be used for breeding.

Anything that blocks or narrows the iridocorneal angle can lead to glaucoma. Narrowing of the iridocorneal angle may be primary ( congenital pathology) or develop secondarily with intraocular tumors, dislocation of the lens, inflammation (anterior uveitis, etc.). In glaucoma in dogs, intraocular pressure increases due to reduced or no outflow of intraocular fluid from the anterior chamber of the eye.

Breed predisposition of dogs to blurred eyes:

• beagle;
• Cocker Spaniel;
• basset hound;
• miniature poodle;
• boston terrier;
• dalmatian.

Primary glaucoma leads to damage to both eyes (even if the dog is marked, the second will be involved in the pathological process after a while). Blurred eyes of the secondary type develops against the background of other diseases:

• conjunctivitis;
• blepharitis;
• uveitis;
• iridocyclitis;
• neoplasms;
• dislocation of the lens;
• hyphema;
• bleeding.

Signs of glaucoma in dogs

In addition to an increase in intraocular pressure, noted during palpation, and an increase in the eyeball, pupil dilation, reflection of the fundus (green cataract), protrusion of the cornea and a violation of its specularity are observed. In chronic cases, retinal atrophy sets in, and the animal loses its sight forever.

Syndromes accompanying blurred eyes:

• eye pain: manifested by blepharospasm, the animal rubs its eyes with its paw and is depressed. The affected eye is usually very painful, especially in the early stages of acute glaucoma. Even in cases where the owner thinks that the animal is not in pain, the pet usually gets better after lowering intraocular pressure (IOP).
• visual impairment: loss of vision may occur within 24-48 hours due to damage to the optic nerve and retinal atrophy. Factors that determine the degree of vision loss include the degree of IOP elevation, the duration of the elevation, and the onset of the disease (acute or chronic).
• Red eye syndrome: redness due to vasodilation of the episclera ± vasodilation of the conjunctiva.
• Corneal edema: Elevated IOP impairs the ability of the corneal endothelium to remove water from the corneal stroma, allowing aqueous humor to enter the stroma, pulling apart the fibers, causing cloudiness.
• Buftalm and linemen: Elevated IOP leads to irreversible stretching of the cornea and sclera. It is most common in young animals. The eye may become so enlarged that it looks unsightly. It is necessary to distinguish buphthalmos from exophthalmos. Buphthalmos is an increase in the size of the eye, while the diameter of the cornea increases. The buphthalmic eyeball can still be retracted into the orbit by applying pressure to the eyelids. With exophthalmos, the size of the eye is normal, but it does not enter the orbit normally, due to neoplasms in the orbit. Linear opacities in the Descemet's membrane are persistent linear breaks in the Descemet's membrane caused by stretching of the cornea. They indicate past or present glaucoma.
• Fixed pupil dilation(mydriasis): As IOP rises (>50 mmHg), the pupillary constrictor muscles become paralyzed, leading to pupillary dilation.
• Dislocation of the lens Dislocation of the lens may occur, causing the development of glaucoma (anterior luxation) or may itself be a consequence of glaucoma. In the latter case. with an increase in the eyeball, the zinn ligament of the lens is torn, which leads to its displacement.
• Chronic anterior uveitis: May cause glaucoma. Normal IOP (15-25 mmHg) in animals with anterior uveitis indicates either concomitant secondary glaucoma or risk of developing glaucoma. Such animals should initially receive antihypertensive agents (thymol or dipivefrin HCL) in addition to corticosteroids. In these cases avoid the use of atropine. If the pupil is narrowed, prescribe dipivefrin HCL. In such cases, it is better to contact an ophthalmologist.

The classic clinical symptoms of chronic glaucoma are buphthalmia, corneal streaks, and cupping of the optic disc. With buphthalmia, the cornea is stretched, linear ruptures of the Descemet's membrane appear, through which the intraocular fluid penetrates into the corneal sclera. Other symptoms of chronic glaucoma are corneal neovascularization following buphthalmia-induced keratitis, luxation and subluxation of the lens, cataracts, vitreous degeneration, and generalized retinal degeneration.

Signs of acute glaucoma:

• blindness;
• eye pain;
• congestion in the conjunctival and episcleral vessels;
• the pupil is usually dilated and does not respond to light stimulation;
• diffuse corneal edema.

Corneal edema associated with acute glaucoma is usually diffuse and affects the entire cornea, turning the eye blue. Edema begins due to a violation of the active endothelial outflow due to increased IOP. and often decreases within a few hours after normalization of intraocular pressure.

Diagnosis of glaucoma - vision test

The diagnosis is based on the detection of elevated intraocular pressure (IOP) and associated clinical signs. In most cases, the diagnosis of glaucoma in dogs is quite simple: intraocular pressure is measured by pressure or tonometry. Sometimes simple tests are used to assess functional vision, such as leading the animal over obstacles with the good eye blindfolded.

And measure IOP using a tonometer. In dogs, normal eye pressure is below 30 mmHg. Art. When using the Schiotz tonometer, to determine IOP, use the calculation table used in humanitarian medicine.

Diagnostic methods:

• slit biomicroscopy at 10x magnification;
• applanation tonometry according to Maklakov;
• electronic tonometry Tonovet.

After the diagnosis is glaucoma, its origin is determined: primary or secondary. Therapy in both cases is different. Onioscopy is the study of the anterior chamber angle of a cloudy eye in a dog. It allows you to determine the etiology of glaucoma: narrowing, underdevelopment of the angle of the anterior chamber of the eye.

Look for clinical signs of anterior uveitis or lens luxation causing glaucoma. Measure IOP in the unaffected eye. An increase in IOP confirms the diagnosis of primary glaucoma.

Determine the visual ability of the animal. If the animal has retained visual ability or is suddenly blind, emergent therapy is performed. The ophthalmologist should perform a fundus examination to assess the condition of the retina and optic nerve to make a prognosis regarding visual ability after IOP is brought under control.

Ultrasound diagnostics

The most accessible and basic method for examining the eye in the presence of opacity of optical means is ultrasound. It is a safe, non-invasive method for evaluating intraocular structures that allows accurate differential diagnosis of canine glaucoma.

Before examining the eyeball, local superficial anesthesia of the eyeball is performed with a 0.5% solution of proxymethacaine. A methylcellulose-based gel is used as a contact medium, which is applied to the end of the sensor. The animal is fixed in a sitting or lying position. The sensor is installed directly on the surface of the cornea for transcorneal scanning and obtaining axial sections.

Survey results:

• displacement of the lens;
• rupture of zinn ligaments;
• hemorrhages in the eye;
• primary luxation of the lens;
• obstruction of the iridocorneal angle;
• lack of a lens;
• accumulation of intraocular fluid in the posterior chamber of the eye.

Treatment of glaucoma and other eye opacities

Choosing the right treatment depends on an accurate diagnosis. Prescribe drugs that lower intraocular pressure (in drops of 0.5% pilocarpine, 0.5% eserip, 1% physostigmine salicylate, etc.). In order to prevent the drying of the cornea, ointments are used - xeroform, yellow-mercury, etc. With excruciating pain, a puncture of the anterior chamber or enucleation of the eyeball is performed. In acute glaucoma of the seeing or partially seeing eye, the goal of treatment is to maintain vision and comfort for as long as possible, using all medical and surgical methods of treatment. In acute cases, IOP should be reduced quickly and effectively.

How is glaucoma treated? emergency and then refer the patient to an ophthalmologist. The goal of treatment is to lower intraocular pressure (IOP). This can be achieved in two ways:

1. By reducing aqueous humor production:
   • Carbonic anhydrase inhibitors: dichlorphenamide, methazolamide;
   • Sympathomimetics: epinephrine, dipivefrin (a derivative of epinephrine);
   • Cyclocryotherapy: (ophthalmologist).
2. By increasing aqueous humor drainage:
   • Cholinergics: pilocarpine;
   • Sympathomimetics: epinephrine;
   • Surgical treatment: (ophthalmologist).

Caution: paracentesis is contraindicated.

Drug treatment is temporary until the surgical correction of the process. Glaucoma is chest controlled medically. In the case of primary glaucoma, a 0.5% solution of timolol 1 drop 2 times a day can be injected into the second eye to prevent the progression of the disease.

Urgent care:

• Mannitol (1-1.5 g/kg IV): 5.0-7.5 ml/kg of a 20% solution over 15-20 minutes helps to significantly reduce IOP within an hour.
• Carbonic anhydrase inhibitors: dichlorphenamide (Daranide) 2–5 mg/kg po 3 times daily in dogs and 1 mg/kg po and methazolamide (Neptazane) 1–2 mg/mg po 3 times daily in dogs and cats. To side effects include metabolic acidosis, vomiting, and dyspnea. Dorzolamide 2% (Trusopt) is a local carbonic anhydrase inhibitor. Enter 1 drop 3 times a day.
• Pilocarpine 2%: administer 1 drop every 30 minutes until the onset of effect (miosis), then every 6 hours. Contraindicated in anterior uveitis or severe iritis.
• Prednisone: It is used for moderate anterior uveitis and to prevent breakdown of the blood-aqueous barrier caused by the myotic drug.
• Sympathomimetics: dipivefrin HCL (Propine) is a derivative of epinephrine, administered 1 drop 2 times a day.
• Timolol 0.25%, 0.5% reduces the production of aqueous humor. Enter 1 drop 2 times a day. May cause bradycardia.

Combined treatment with pilocarpine and epinephrine has proven to be very effective in dogs. Most often in glaucoma, topical atropine is contraindicated.

The operation is carried out even in blind animals, since glaucoma is a very painful disease.

• Cyclo-destructive operations: cyclocryotherapy or cyclophotocoagulation (laser) - these methods may be useful to preserve residual vision in the sighted eye. After surgery, you may need to continue medical therapy.
• Intraocular prosthetics is a cosmetic procedure on a blind, painful eye.
• Enucleation with or without prosthetics for a blind and/or painful eye.

Cyclodestructive procedures are transscleral cryosurgery and laser cyclophotocoagulation. Cryosurgery is effective in lowering IOP, but causes many complications - cataract formation, severe uveitis, hypotension. Filtering surgical procedures are sclerotomy with iridenclesis and gonioimplantable device.

Surgical treatment of seeing or partially seeing eyes with dislocation/subluxation of the lens in the early stages of glaucoma remains controversial. There are doubts whether urgent surgical intervention (intracapsular linsectomy) and medical reduction of IOP is required for acute lens luxation in the anterior chamber of the seeing eye to prevent pupil-blocking glaucoma.

Laser CPA allows you to save vision in a glaucomatous eye for a longer time than drug therapy alone. It is also used for the preventive treatment of other healthy eyes in the case of primary glaucoma, but there is a risk of loss of vision in this eye as a result of postoperative pressure rise and uveitis.

Preserving surgical procedures in blind eyes with glaucoma are enucleation, intraocular evisceration-implantation, and pharmacological ablation of the ciliary body by injecting gentamicin into the vitreous body. This procedure always has successful results and gives a completely cosmetic appearance and comfort to the eyeball, which does not require further treatment.

Despite recent advances in the treatment of glaucoma. This disease remains one of the most difficult, both for the doctor and for the owner. In the treatment of all cases of glaucoma, prompt consultations with veterinary ophthalmologists are necessary.

Of all pets, dogs are the most susceptible to this. eye disease like glaucoma. More specifically, the canine proportion of glaucoma patients is about 80%. From this we can conclude that the owners should be more attentive to the condition of the eyes of their pets, paying attention to even minor changes in their behavior caused by visual discomfort.

Know the enemy "by sight"

Glaucoma outwardly is a gray-green clouding of the lens, and in essence this disease threatens the dog with loss of vision - first peripheral, and then central. Mechanism this process, characterized primarily by irreversibility, is as follows:

• 1. Drainage processes in the eye are disturbed, as a result of which the so-called aqueous humor creates a significant increase in the pressure of the fundus.
• 2. As a result, the vessels of the eye are compressed and, as a result, the supply of its tissues with oxygen becomes insufficient for its normal functioning. There is ophthalmohypertension (increased intraocular pressure), leading, among other things, to atrophy of the optic nerve.
• 3. The cells of the eye responsible for the "translation" of the outside world to the visual parts of the brain die.

This process can proceed slowly and imperceptibly for the animal - largely due to the increased work of other senses - but it is irreversible, and this is the main danger.

That's why early diagnosis this disease so important. Most often, with timely access to a veterinary ophthalmologist, the dog's vision can be preserved.

risk zone

Unfortunately, in most cases clinical picture canine glaucoma is rather vague: the disease develops very slowly, and in its initial stages, the dog may not be bothered by anything. In order to ensure the proper level of preventive measures under this condition, in addition to the need for regular examination by a canine ophthalmologist, the following points should be taken into account:

• 1. The age of the dog. Animals older than 6 years are most susceptible to the development of glaucoma. Therefore, an elderly pet should be diagnosed more often for glaucoma changes in the structure of the eye.
• 2. Breed of the dog. There are a number of breeds whose propensity for glaucoma is higher than that of their relatives. These are, first of all, cocker spaniels and beagles, as well as divers, chihuahuas and some others.
• 3. Genetic predisposition. This factor is of great importance in the development of glaucoma, so it is useful to find out if any of your dog's immediate ancestors suffered from this disease. For the same reason, the treatment of one patient with glaucoma of the eye must necessarily take place in conjunction with preventive measures aimed at preserving the second eye.
• 4. The presence of chronic (or newly emerged) inflammatory eye diseases. There are cases when the most common conjunctivitis caused irreversible glaucoma changes. The risk is greatly increased as a result of the treatment of the above diseases with steroidal anti-inflammatory drugs. In this case, acute glaucoma can develop within a month.
• 5. Diagnosing a dog with diabetes, one or another cardiovascular disorder, as well as hypertension.
• 6. The presence of facts of eye injury. In this case, the risk of glaucoma is extremely high, and visual impairment is irreversible.

Glaucoma symptoms and treatment

You should be alert to the following symptoms in your pet:

• Increased lacrimation.
• An increase in the volume of the eyeball (the so-called "bull's eye").
• Protruding scleral vessels that become bright and tortuous (cobra syndrome).
• Soreness of the eye, manifested in the fact that the dog does not allow touching the head from the side of the diseased eye.
• Loss of mood and appetite, depression and avoidance of contact with people and other animals.
• Disorientation of the dog in space.
• Photophobia, expressed in the desire to climb into a dark corner and put his head in his paws, or curl up in a ball.

In some cases, the doctor prescribes eye drops to the animal, the action of which is aimed at reducing intraocular pressure. This is enough to return it to the normal range and save the dog from discomfort. In some cases, drugs are additionally prescribed that reduce the production of aqueous humor: this also significantly improves the patient's condition.

As for visual functions, they can also be saved. However, it is important to understand here that a complete cure is unlikely to occur, and the drug will most likely have to be used for life. Roughly speaking, the acute form of glaucoma with such treatment turns into a chronic, but well controlled.

If the visual function is already irretrievably lost, or the prescribed drug treatment does not justify the hopes placed on it, and the eye has an unattractive appearance, it makes sense to perform a surgical intervention - evisceration. In this case, instead of the removed eye, the dog will be inserted into an implant, due to which the achievement of the necessary cosmetic effect is guaranteed.

Be that as it may, before prescribing the appropriate treatment, as well as in its process, the veterinary ophthalmologist must necessarily monitor the intraocular pressure and the condition of the fundus. Their dynamics will make it possible to judge in the future the course of the disease and the effectiveness of the prescribed treatment.